Surgical Procedures


Apart from extractions for crowding or to correct a protrusion etc., the most usual surgical procedure that orthodontic patients undergo is the removal of wisdom teeth.

For most adolescents, this occurs sometime after they have completed their orthodontic treatment. Those who start their orthodontic treatment later in adolescence or as an adult may have wisdom teeth removed when treatment starts if appropriate.

xray of teeth - surgical proceduresUsually the wisdom teeth are removed because they do not have enough room to erupt fully. If they are only partially erupted and are partly under a gum flap, they are prone to gum infections and decay as it is very difficult to clean under the gum. The wisdom teeth may be more deeply impacted under the gum and in the bone, adjacent to the roots of the second molar in front. If impacted wisdom teeth remain in this position, bacteria and broken down food may have access to the crown of the wisdom tooth through the gum. This can cause decay in the wisdom tooth and in the second molar in an inaccessible position.  There may also be loss of bone support for the second molar.

Over time, an impacted wisdom tooth may erode into the back of the root and crown of the molar in front, often destroying this tooth.  This can be seen in the radiograph to the left where the upper left wisdom tooth has damaged the back of the molar in front.  The lower right wisdom tooth is also impacted. 

Canine Impactions

Developing canines sometimes erupt off-track and try to emerge at a distance from the deciduous canine which they should normally dislodge. The upper canines have a long pathway of eruption and can become stuck on the roof of the mouth, near to the root of the upper lateral incisor.

canine eruptions xray

Upper canines can also try to emerge on the lip side of the lateral incisor (second tooth from the front), often high up under the lip. Lower canines impact much less frequently but can move right across in front of the roots of the lower incisors.

canine eruptions imageIn this image you will see: The lower left canine is impacted in front of the lower incisor while the right canine is behind.

Orthodontic treatment would involve the surgical uncovering of the canine. A dressing is placed over the tooth until the gum has healed. The orthodontist can then place a bracket on the tooth and can pull it into place using braces on all the other teeth.

If the canine is too deep, the surgeon will bond a bracket on the crown of the canine. A gold chain is attached to the bracket and this chain comes through the gum and the gum is sutured back over the canine. Using braces on all the other teeth, the orthodontist uses the gold chain to pull the canine into place.

Other teeth that may be impacted include upper central incisors, upper and lower premolars and lower second molars. Braces are used to retrieve these teeth or to close spaces if they have to be extracted because they cannot be retrieved.

JAW SURGERY OR ORTHOGNATHIC SURGERY

Orthognathic surgery is a specialised branch of oral and maxillofacial surgery that is concerned with the correct positioning of the upper and lower jaws and their teeth in relation to each other and the remainder of the face.

A small percentage of orthodontic patients have a jaw difference that is so great that, if they were treated by braces alone,

a)   the teeth would have to be moved into a poor position in relation to the surrounding bone and gums which could lead to later gum recession and some return of the original problem;  and/or
b)    full correction of the original problem could not be achieved, leaving a partial result (which would be prone to relapse) or even a different problem;   and/or
c)   the appearance of the final result would be adverse and unattractive for the patient.

These patients can be treated by a combination of braces and jaw surgery. The braces are used to correct any crowding, spacing, rotations of the teeth or other irregularities before the jaw surgery. The most important role of the braces is to place the upper and lower front teeth in the best position within the upper and lower jaws so that when the jaws are repositioned, the teeth are then correct in the remainder of the face and in relation to each other, upper against lower. This pre-surgical repositioning of the teeth is called “decompensation”.  This orthodontic stage of the overall treatment does not attempt to correct or compensate for the jaw differences.  The surgery will do this stage of the correction.

The usual procedure for those having jaw surgery involves the initial placement of braces to correct the teeth (extractions may be needed) over a few months. When the teeth have been fully aligned within each jaw, the surgery is carried out with the braces still on the teeth. The surgery is done all completely inside the mouth and there are no scars on the outside. The surgeon uses the braces to control the new jaw positions with elastic bands and to settle the teeth after the surgery. So the braces continue for several months after the surgery.

The technical details of each of the surgical procedures are shown in the Dolphin videos with each of the descriptions of jaw problems outlined below.

Small Lower Jaw

For most people with protruding upper front teeth, this protrusion is a combination of the upper front teeth being forward a little bit in the upper jaw and the lower jaw itself being back in relation to the upper jaw. If the difference between the upper and lower front teeth is not too great, braces can correct the bite by moving the upper and lower teeth only, in effect camouflaging or compensating for the difference between the jaws.

However, in cases where the jaw difference is too great, consideration needs to be given to the surgical repositioning of the tooth-bearing portion of the lower jaw to correct its position with the upper front teeth. This will also place the lower jaw in an attractive position with the remainder of the face.

Prominent Lower Jaw

Orthodontic camouflage for patients with a prominent lower jaw is much more limited than for those who have protruding upper front teeth. For a patient whose lower front teeth bite ahead of the uppers, the amount that the upper front teeth can be tipped forward and the lower front teeth tipped back is very limited. Apart from creating an unattractive result, gum recession on the front of these teeth can be an increased risk. Orthognathic surgery for the correction of these "Skeletal III"  jaw discrepancies is only carried out when it is considered that the patient has, as far as one can tell, completed jaw growth. In males this is usually from 18 years and about 16 years for females.

Although the lower jaw may appear to be prominent in approximately 40% of cases, the upper jaw is often also back a little in the face. Therefore, the correction may involve surgical forward movement of the tooth-bearing portion of the upper jaw along with backwards movement of the lower jaw.  Otherwise it may just involve the backwards movement of the lower jaw or, less often, the forward movement of the upper jaw only.

Facial Asymmetry

Jaw surgery may be required to correct a facial asymmetry where the lower jaw or chin point is noticeably off to one side compared to the nose or upper lip or the level of the eyes.  If the upper arch of teeth is tipped as a compensation for the lower jaw position, a surgical procedure involves moving both jaws.

Vertical Maxillary Excess

Some people on smiling show an excessive amount of gum between the upper lip and the teeth and this is often associated with a longish, narrow face. The surgery involves moving the tooth-bearing portion of the upper jaw up, under the upper lip and then positioning the lower jaw and chin point to match this new position.

Anterior Openbite

A severe functional problem arises when only the back teeth meet when a person tries to bite together. The lack of any vertical overlap or contact between the front teeth is known as an anterior openbite. The surgery for this jaw discrepancy is similar to that for vertical maxillary excess.

MINI-IMPLANTS, MINI-PLATES OR TEMPORARY ANCHORAGE DEVICES

Mini-implants or mini-screws are small, specially designed screws that are placed in the bone between the teeth. As they are anchored in the bone, they can act as a very strong anchor, allowing the orthodontist to use elastics or springs to move a group of teeth or a tooth without placing any strain on any of the other teeth. This technique can allow tooth movements that otherwise could not be carried out or would take too long. Relatively few patients require these appliances but, when used, they can make an otherwise impossible treatment become a successful treatment.

The mini-screws are placed with only a little local anesthetic in a relatively minor procedure.

Mini-plates require a little more surgery for their placement as part of the plate is under the gum. Their main advantage is that they stay in place longer than mini-screws, which are more prone to loosening. They can also be placed further away from the roots of the teeth, ensuring no damage.
除了拔牙去纠正牙齿拥挤和前突,最常见的手术治疗在矫 正中是拔除智慧牙。

xray of teeth - surgical procedures大部分的青少年在做完矫正治疗后才拔智慧牙。有些开始 矫正治疗比较晚或者成年人可能在治疗前拔智慧牙。

通常智慧牙需要拔除,因为它们没有足够的空间生长出来。如果它们只是一部分萌出,另一部分在牙龈下面,会引起 牙龈发炎和蛀牙因为很难清洁。如果智慧牙完全在牙龈或 骨头里,它们会损伤第二磨牙的牙根,如果它们长期留在 那里,细菌会通过牙龈到智慧牙引起蛀牙,还会造成第二 磨牙的牙槽骨丢失。
 
请看下面的X 光。上颌左面的智慧牙损伤了后面第二磨牙。

下颌右面的智慧牙也阻生了。 

尖牙阻生

尖牙会错位生长,有时会从上颌萌出,甚至碰到侧前牙。

上尖牙有时会从唇侧萌出。

canine eruptions xray

下尖牙阻生比例比较小但有时候可以横在下前牙牙根上。

canine eruptions image请看这个X 光片。左下尖
牙在下前牙的前面而右尖
牙的后面。

 

矫正治疗有时候需要做手术暴露尖牙,矫正医生会粘上托槽然后把牙齿拉到准确位 置上。

如果尖牙太深,口外医生会把托槽粘在尖牙的牙冠上,有 一根金属链从牙龈里拉出来。矫正医生会利用金属链把牙 齿拉到准确的位置。

其他牙齿包括上前牙,上下前磨牙等也可能阻生。我们就 用固定矫正器来移动这些牙齿。

颌骨手术

颌骨手术是由口外专科医生来纠正上下颌骨的咬合位置以 改善脸部的形态。

小部分的病人如果只用矫正器治疗会产生以下的不良效 果:

1. 牙齿会移到不容易长期维持的位置,以后可能会造成牙龈萎缩。
2. 治疗不彻底
3. 最后的效果不理想

这些病人最好是用固定矫正器配合颌骨手术治疗。用固定 矫正器先纠正拥挤,牙齿缝隙,牙齿旋转等问题,然后做 颌骨手术。最重要的是用固定矫正器把牙齿移动到准确的 位置,等做完颌骨手术后仍然保持牙齿在理想的位置。

通常需要手术治疗的病人是需要先用固定矫正器把上下牙 齿拉到手术所需的位置,然后戴着固定矫正器手术。手术 全部都在口腔中进行所以不会在脸部留下疤痕。口外医生会用固定矫正器和橡皮圈来保持新的颌骨位置。做完手术还需要戴固定矫正器几个月

下面是一些手术治疗的介绍。

下颌过小

通常有上牙前突的病人是因为上前牙比上颌骨突出而下颌 骨后缩。如果上下的差距不是过大,可以用移动牙齿来纠 正。

如果差距太大,就需要用手术来纠正上下颌骨的位置,使下颌骨移到理想的位置。

下颌骨突出

下颌突出只用固定矫正器治疗要比上颌突出的病人难。如 果病人的下前牙在上前的前面,要把下前牙冠往里移比较 难,效果不理想也会引起牙龈萎缩。这类病人如需手术治 疗必须等到颌骨生长发育完成,男性大概18 岁,女性16 岁。

尽管其他部分病人也会觉得是下颌太突出,但其实40%的 病例是由于上颌后縮。所以可以用手术把上颌骨往前移,下颌骨往后移,或则只需要移上或下颌骨。

脸部不对称

有时候,下巴,鼻子,嘴唇和牙齿中线不对称,通常需要 颌骨手术来纠正上下颌骨的位置。

上颌骨的高度过高

有些病人在微笑是会露出过多上牙龈,通常在长而窄的脸 型中比较多,需要手术把上颌骨提高。

前牙张开咬合

当咬合是只有后牙咬在一起,前牙是张开的是非常影响咬 合功能的。手术治疗和上颌骨过高是相似的。

微小的种植钉, 微小基板 或(临时的锚基装置)

微小的种植体是一种特殊设计的小金属钉,种植在牙齿之 间的牙槽骨里,是一个非常有力的支点用来移动其他的牙 齿。用这种支点可以又快又好的移动牙齿使治疗成功完成。

通常放微小种植体需要用局部麻醉。

微小基板需要通过手术种植到牙龈下面。它们主要的优点 是可以放的时间长久而且不容易松动而且远离牙根。__